We’ve burned 2x as many fossil fuels as needed to account for the observed rise (the rest has gone into the ocean and is causing ocean acidification).

CO2 Traps Heat

We have known this to be true for over 150 years (since 1859), since Irish scientist John Tyndall stuck some CO2 in a tube, shone some light through it, and found that the temperature rose higher when there was more CO2 [1, 2].

The Concentration of CO2 is Rising

The second point we’ve been seeing thanks to the direct measurements of the Keeling Curve, which now records 400 ppm of CO2 in the atmosphere, up from 317 in 1958 when measurements began [3, 4].

Observed Rise of CO2

The third we know because of oil, coal, and gas company accountants. They record how much they sell, and if you assume all that they sell is burned (a good assumption), you end up with enough fossil CO2 in the atmosphere to double the rise we’ve seen [5, 6].

These three facts are so obvious that they were apparent as early as 1895, when Chemist Svante Arrhenius became the first to predict rising temperature due to human additions of CO2 to the atmosphere [7].